Methylxanthine and polyphenol distribution in guarana cultivars

Guarana is a plant a native to the Amazon, and its seeds are used as soft drinks and other energy drink ingredients. The phytochemical aspects of guarana have been extensively explored for its use in herbal and cosmetic compositions due to the presence of metabolites, such as methylxanthines and polyphenols. This work aims to fill a gap in the information about the presence and accumulation of methylxanthines and polyphenols in leaves and fruits of guarana cultivars. Thus, information will be generated to contribute for future studies on guarana genetic improvement and plant physiology. Methylxanthines (caffeine [Cf], theobromine [Tb], and theophylline [Tf]) and phenolic compounds (catechin [Ct] and epicatechin [EC]) were quantified by HPLC in the leaves and fruits (pericarp and seed) of eighteen guarana cultivars. Tf was not detected in any tissue. Caffeine is present almost exclusively in seeds (4.21 ± 0.69 g.100g dry weight-1), while theobromine is predominant in leaves. Although catechin and epicatechin are present in both tissues, their contents are higher in seeds, with mean values of 1.36 and 0.76 g.100g dry weight-1, respectively. In guarana cultivars under study, BRS-Satere and BRS-608 stood out due to the high caffeine and phenolic contents in seeds. On the other hand, in BRS-Luzeia cultivar, the highest catechin and epicatechin contents were observed in leaves.  The results provide new perspectives for the commercial exploitation of other guarana tissues, which could favor the industry, since the main source of these compounds are guarana seeds.